1. Technical Field
The present invention relates to a light measurement device provided with a tunable interference filter that extracts, from an incident light, a light with a predetermined wavelength.
2. Related Art
In the past, an interference filter that makes a pair of reflection coatings face each other and transmits or reflects a light of an incident light, the light with a predetermined wavelength which was intensified by multiple interference by the pair of reflection coatings, has been known (see, for example, JP-A-2009-251105 (Patent Document 1)).
In an optical filter apparatus described in Patent Document 1, a pair of substrates are made to face each other, and one of the substrates is provided with a movable section (a first portion) and a diaphragm (a second portion) that holds the movable section in such a way that the movable section can move with respect to the other substrate. On the movable section, one of a pair of reflection coatings (mirrors) is formed, and, on the other substrate, the other reflection coating facing the reflection coating formed on the movable section is formed. In such an optical filter apparatus, a gap dimension between the pair of reflection coatings can be changed by moving the movable section, whereby it is possible to extract a light according to the gap dimension.
Incidentally, in Patent Document 1, when the gap between the reflection coatings is changed, the movable section held by the diaphragm is bent toward the other substrate by electrostatic attraction. In this case, the movable section is moved toward the other substrate by bending of the diaphragm, and, at this time, the movable section also bends slightly, which makes the mirror provided on the movable section also bend. This makes it impossible to make the gap dimension between the pair of reflection coatings uniform and allows lights with different wavelengths to pass depending on the position in the reflection coating, causing a reduction in resolution. In this case, when an imaging sensor formed of a plurality of imaging devices is provided so as to face the interference filter, the wavelengths of the lights which enter the imaging devices differ from one another, making it impossible to grasp accurately the amount of light with a wavelength to be detected.